A growing number of professional athletes -- some living and some deceased -- have donated or announced their intention to donate their brains to science. They're hoping to advance the research on chronic traumatic encephalopathy (CTE), a degenerative brain disease associated with head injuries. Included in that group are former NFL stars Frank Gifford, Ken Stabler, and Junior Seau (pictured here), who were diagnosed with CTE after their deaths.
CTE is marked by depression, dementia, and other Alzheimer's-like symptoms. It can only be definitively diagnosed after death.
Here is a look at some of the athletes aiding the research.
Olympic medal-winning cyclist Kelly Catlin died at age 23, reportedly by suicide, in March 2019. The Washington Post reports her family donated her brain to the Veterans Affairs-Boston University-Concussion Legacy Foundation Brain Bank "to investigate any possible damage caused by her recent head injury and seek explanations for recent neurological symptoms."
It was announced March 3, 2016 that retired soccer player Brandi Chastain, seen here celebrating scoring the winning goal in the 1999 World Cup final against China, has decided to donate her brain to the Massachusetts-based Concussion Legacy Foundation. Upon her death, her brain will go to the VA-BU-CLF Brain Bank, a joint project with the Department of Veterans Affairs and Boston University School of Medicine. Researchers believe that heading the ball can lead to the disease.
In youth soccer, the Concussion Legacy Foundation says, that heading the ball is responsible for one third of all concussions. U.S. Soccer announced in 2015 that it banned headers for young players under 11-years-old.
To date, no female athletes have been found to have had CTE.
Cindy Parlow Cone
Brandi Chastain joins Cindy Parlow Cone as the second former Team USA member to donate her brain to research.
Cone, a World Cup champion and Olympic gold-medalist, frequently headed the ball, suffering a number of head injuries, including concussions, throughout her career. Her career came to an abrupt end in 2004 after suffering what doctors called a mini-stroke, concussion-related, in her 20s. She says she experienced tingling in her fingers after one particular hard header in a match in 2001 and suffered at least two blackouts on other occasions. She still suffers from headaches and fatigue.
Former Oakland Raiders quarterback Ken Stabler, the late NFL and Super Bowl MVP and a finalist for the Pro Football Hall of Fame, had the brain disease CTE, Boston University researchers reported February 3, 2016.
Stabler, who died of colon cancer at age 69 in July 2015, had Stage 3 chronic traumatic encephalopathy, Dr. Ann McKee told The Associated Press. The former football star told his family he wanted his brain studied after learning that former NFL linebacker Junior Seau was diagnosed with the disease. Seau shot himself in the chest and died at age 43.
"What is interesting about Ken Stabler is that he anticipated his diagnosis years in advance," Chris Nowinski, the founder of the Concussion Legacy Foundation, told the AP. "And even though he's a football icon he began actively distancing himself from game in his final years, expressing hope that his grandsons would choose not to play."
NFL Hall of Famer and TV sports commentator Frank Gifford, who played for the New York Giants for 12 years beginning in 1952, died in August 2015 at the age of 83. Gifford became one of the highest profile former NFL players to be named as having CTE.
His family revealed in November 2015 that Giffford suffered from concussion-related brain disease. Gifford's family said they suspected he'd been "suffering from the debilitating effects of head trauma" while he was alive.
In 2015, researchers at Boston University confirmed CTE in the brains of 87 out of 91 deceased former NFL players tested. "While we know on average that certain positions experience more repetitive head impacts and are more likely at greater risk for CTE, no position is immune," Dr. Ann McKee, a professor of neurology at Boston University, told the AP.
Professional wrestler Chris Benoit killed his wife and seven year-old son, before turning the gun on himself at home on June 24, 2007.
Medical experts affiliated with the Sports Legacy Institute revealed in Sept. 2007 that Benoit had CTE in all regions of his brain. Benoit's medical history included multiple concussions.
Canadian Derek Boogaard played for the New York Rangers and the Minnesota Wild in the NHL and was known mainly as an enforcer. His death was caused by a drug and alcohol overdose at the age of 28 in 2011. After testing at a lab at Bedford V.A. Medical Center in Bedford, MA it was found he had CTE.
According to the New York Times, he was the fourth of four hockey players whose brains were examined to have CTE.
Former Chicago Blackhawks and Detroit Red Wings player Bob Probert died of heart failure in 2010, but before his death he asked his wife to donate his brain to CTE research. He died in 2010. Researchers at Boston University found that Probert had the disease in 2011.
Former Iowa football star Tyler Sash, who later played two seasons as a safety for the New York Giants, was found dead at his home of an accidental overdose of pain medication at the age of 27 on September 8, 2015.
His family announced, January 27, 2016, that representatives from Boston University and the Concussion Legacy Foundation found Chronic Traumatic Encephalopathy (CTE) in his brain.
According to the New York Times Sash had been cut by the Giants after what was at least his fifth concussion and the disease had advanced to a stage rarely seen in someone that age.
"Iron Mike" Webster helped the Steelers win four Super Bowls in the 70's. After leaving the game, he suffered depression and dementia, dying in 2002 at the age of 50. He became the first apparent case of "footballer's dementia" for Brain Injury Research Institute (BIRI) pathologist Dr. Bennett Omalu (who was later portrayed by Will Smith in the movie "Concussion"). Webster's brain was said to have been through the equivalent of "25,000 car crashes" over his 25 years of playing football in high school, college, and the NFL.
Chicago Blackhawks player Steve Montador retired from the NHL soon after suffering a debilitating concussion in 2012. He often fought on the ice. It was determined in 2015 after his death that February at 35-years-old that he suffered from CTE. According to the Toronto Star, Montador offered his brain for research at the age of 31. He reportedly suffered from depression which has been linked to CTE.
Montador played in the NHL for 10 years for the Blackhawks and several other teams.
Safety Dave Duerson won a Super Bowl as part of the 1985 Bears defense. In February 2011, Duerson, 50, texted to his ex-wife Alicia an odd request: "Please, see that my brain is given to the N.F.L.'s brain bank." When Duerson's body was found, there was a handwritten suicide note repeating the request. "I think David knew that inside of him there was something wrong," Alicia told the New York Times.
Duerson's family complied with his last request, donating his brain to the Center for the Study of Traumatic Encephalopathy (CSTE). In May 2011, doctors at the CSTE confirmed Duerson had "indisputable evidence" of CTE.
Bengals wide receiver Chris Henry's death - after falling from a truck during a domestic dispute in 2009 - shocked football fans. An autopsy by the BIRI found that the 26-year-old had chronic traumatic encephalopathy.
"I was surprised in a way because of his age and because he was not known as a concussion sufferer or a big hitter. Is there some lower threshold when you become at risk for this disease? I'm struggling to see if something can come out positive out of this," Dr. Julian Bailes of the BIRI grimly told the New York Times.
Strzelczyk was an offensive lineman with the Steelers for eight seasons. In 2004, he died in a car crash after taking police on a high-speed chase, the Pittsburgh Post-Gazette reported. Toxicology reports showed no evidence of drugs or alcohol in the 36-year-old's body. So what caused his erratic behavior?
Strzelczyk's family donated his brain to the Brain Injury Research Institute. Dr. Ronald Hamilton of the University of Pittsburgh told the New York Times, "If I didn't know anything about this case and I looked at the slides, I would have asked, 'Was this patient a boxer?'"
Long played right guard for the Steelers from 1984 to 1991. In 2005, when he was 45, he killed himself by drinking antifreeze, the Pittsburgh Post Gazette reported.
The Brain Injury Research Institute examined his brain and saw evidence of damage that might well have contributed to his suicide. "Terry Long committed suicide due to the chronic traumatic encephalopathy due to his long-term play." Dr. Bennet Omalu told the newspaper.
Waters was regarded as one of the league's hardest-hitting defensive backs during his career with the Philadelphia Eagles. He committed suicide in 2006, at the age of 44.
An autopsy showed that his brain tissue to be similar to that of an 85-year-old's Alzheimer's patient, Dr. Bennet Omalu told the New York Times. "If Waters had lived another 10 to 15 years, he would have been "fully incapacitated," Omalu said.
When former Houston Oilers linebacker John Grimsley died in 2008 at the age of 45, his wife donated his brain to the Center for the Study of Traumatic Encephalopathy. An autopsy revealed brain abnormalities typically seen in elderly Alzheimer's patients. The site compares slides of Grimsley's brain tissue to those of a 73-year-old ex-boxer.
The former Patriots linebacker and three-time Super Bowl winner Ted Johnson, who retired from football after back-to-back concussions in 2002, told CNN he has battled anger, depression and Alzheimer's like symptoms - symptoms he blames on football.
He decided he would donate his brain to the CSTE once he died. "I'm not trying to reach up from the grave and get the N.F.L. But any doctor who doesn't connect concussions with long-term effects should be ashamed of themselves." Johnson told the New York Times.
Matt Birk, 34, is a six-time Pro Bowler for the Minnesota Vikings who went on to play for the Baltimore Ravens where he helped win a Super Bowl Championship. He retired in 2013. Birk became the NFL director of football development in 2014.
His greatest contribution to the game might not fill a stat sheet, though. In 2013, after being asked, he agreed to donate his brain after death, telling the Associated Press, "The decision to do this brain donation, if it can help make the game safer for future generations, than why not?"
When Brent Boyd was playing the 1980's as an offensive guard for the Minnesota Vikings, brain injury awareness was an afterthought. "We didn't even know what a concussion was ... you got your bell rung, you got dinged," Boyd told CBS News.
After hearing of other players' deaths following apparent neurological problems, Boyd realized where his depression, dizziness, and headaches might be coming from. His struggle led him to found an important advocacy group called Dignity After Football for NFL retirees and their families. His work on behalf of football players has included three Congressional testimonies on concussion injuries and is considered instrumental in recognizing the medical issues related to concussion injuries. When he told the House Judiciary Committee that the NFL and the NFL Players' Association strategy on the issue was "Delay, Deny and Hope they Die!" it became a slogan in the fight waged by NFL retirees.
He also agreed to donate his brain to the CSTE.
Sean Morey's 10-year career as a special teams ace came to an abrupt halt in 2010 when "post-concussion syndrome" forced his retirement. Even though he was no longer playing, he told Sports Illustrated that he felt like he had just "made six or seven tackles."
His experience led him to donate his brain to the CSTE. "One of the most profound actions I can take personally is to donate my brain to help ensure the safety and welfare of active, retired, and future athletes for decades to come." Morey said in a 2009 written statement.
In 2014, Morey was part of a group of seven plaintiffs, who filed a formal objection to the $765 million NFL Players' Concussion Injury and Proposed Settlement calling it a "lousy" deal which didn't offer enough, prior to formal approval of the agreement. The settlement was meant to resolve concussion-related lawsuits and fund medical exams, concussion-related compensation and medical research.
The appeal failed, but only after the NFL removed the $675 million cap (part of the $765 million settlement) on damages in response to a federal judge questioning if the figure was enough to cover an estimated 20,000 retired players.
Former player Zach Thomas was a Pro-Bowl linebacker for the Miami Dolphins from 1996-2008. In 2010, he joined several others on the CSTE's living donor registry. "I want to do my part to help the researchers understand this disease and to discover treatments and an eventual cure," he said in 2010 written statement.
Kyle Turley played offensive tackle for the Saints, Rams, and Chiefs during his 10-year NFL career which began in 1998. He's been in the spotlight talking about the debilitating effects the hits he took as a player have had on his body, and his decision to support this cause.
"If I can donate my brain to this situation, this cause, I'm helping my boy out. I want him to be able to grow up and at least have a chance, you know, not be facing these things that I've been facing" Turley said in a 2010 interview with Arrowhead Addict, a Chiefs fan blog.
Junior Seau, one of the NFL's best and fiercest players for nearly two decades, had a degenerative brain disease when he committed suicide in May 2013, the National Institutes of Health revealed.
Results of an NIH study of Seau's brain revealed abnormalities consistent with chronic traumatic encephalopathy (CTE). The NIH, based in Bethesda, Maryland, conducted a study of three unidentified brains, one of which was Seau's. It said the findings on Seau were similar to autopsies of people "with exposure to repetitive head injuries."
Atlanta Falcons safety Ray Easterling, who helped lead the team's vaunted defense in the 1970s and later filed a high-profile lawsuit against the NFL targeting the league's handling of concussion-related injuries, committed suicide on April 19, 2012, in Richmond, Va. He was 62.
After his career, he suffered from dementia, depression and insomnia, according to his wife, Mary Ann. An autopsy in 2012 revealed that Easterling suffered from CTE.
Ralph Wenzel, who played guard for the Pittsburg Steelers and San Diego Chargers for seven seasons in the 60s and 70s, died in June 2012 from complications of dementia, according to his wife, Eleanor Perfetto. He was 69. According to the New York Times, Wenzel started having signs of early-onset dementia - memory lapses and other cognitive problems - at age 52 in 1995. The former player's condition became so severe he stopped working as a teacher and coach and was institutionalized in 2006.
Wenzel's brain is among more than 100 that have been donated to the Boston University brain bank. His case was discussed at a October 2009 House Judiciary Committee hearing.